1. Field of the Invention
This invention relates to a method for producing a pumpable solid fuel for small furnaces in the form of a coal/liquid slurry containing various additives to improve its ignition, minimize SO.sub.x emmision, and control its flow properties in finely divided form.
2. Review of the Prior Art
At the present time, petroleum imports account for more than 40% of United States usage. At any time, this supply could be curtailed or eliminated by political or military action. Even if such an emergency situation does not develop, liquid hydrocarbon fuels could become increasingly scarce in view of government policies that affect domestic exploration, development, and refining. As such scarcity develops, stationary furnaces and power plants, including domestic and commercial furnaces for space heating and hot water, will tend to be fueled with solid fuels, particularly coals and other bio-mass such as wood products.
As the gaseous and liquid fuels become more and more scarce in the future, solid fuels, principally coal, will have to be used more and more extensively. Coal already is playing an ever increasing role in fueling power plants. However, it is much more difficult to use coal in small furnaces. The problems include handling, transporting, burning and emissions, particularly SO.sub.x. To facilitate the use of coal in small furnaces U.S. Pat. No. 4,210,423 discloses a method for preparing solid fuel in either powder or briquette form. Copending application to Yan et al., Ser. No. 413,572, filed Aug. 31, 1982, discloses a method for producing an improved coal/water slurry by contacting run-of-mined coal with a mixture of an alkali and an organic solvent, pulverizing the treated coal to a predetermined particle size and slurrying the pulverized coal with water to form a pumpable, coal/water slurry having improved burning quality and SO.sub.x abatement and is stable in storage.
From the viewpoint of handling coal for small furnaces, the solid fuel in a pumpable form would be preferred. The present invention enables coal to be formulated in a stable, pumpable form. The formulated fuel also contains additives for SO.sub.x abatement, for ignition and oxidation promotion, and ash modifiers to improve the combustion quality of the fuel.